Method for curling yarn



Sept., 2, 1941. A. l.. JOHNSTON, JR 2,254,895

METHOD FOR URLING YARN Filed lAug. l5, 1938 l ATTORNEYS .Patented Sept.2, 1941 UNITED STATES PATENT vOFI-ICE METHOD FOR CURLING YARNAndrewlLangstaile Johnston, Jr., Plainfield, N. J.

Application August 15, 1938, Serial No. 224,868

11 Claims.

'I'he present invention relates to a process for producing asubstantially permanent curl or kink in yarn and like materials and toapparatus-for use in practicing the process.

The method heretofore most commonly em,- ployed commercially for curlingyarn consists in combining a number of yarns as, for example, twenty tofifty, into a bundle, twisting the bundle under not too great tensionuntil, as the twist increases, the bundle forms into a nearly continuoushelix. Thegyarn so twisted is steeped (boiled oi) in boiling water orsteam or other solvent with or without the addition of setting agents toset the curl. In the case of mohair yarn which is practically the onlyyarn curled on a commercial scale this steeping requires from six toeight hours at substantially boiling temperature to produce a permanentset of the curl. Ordinarily the yarn is dried while still twisted andthen untwisted, the whole process requiring some ten or twelve separateoperations. The long steeping required in this process to set the curlcauses a considerable deterioration of theyarn, reducing the tensilestrength about 20% during the rst hour and about 5% for each additionalhour. The elongation properties suier an even greatervdeterioration andafter a seven hours steeping the physical properties of the yarn' aredepleted to the extent of 50% and this is `reiected in the wearingquality of the woven fabric. Furthermore, the yarn shrinks to the extentof 5% or more, thus correspondingly increasing the amount of yarnnecessary to produce a given yardage.

In the operation of this process the limit to the length which it ispracticable to curl is about 1200 yards, requiring tying where greaterlengths are required in weaving. All things considered,

the speed of production is decidedly limited, the product is inferiorandthecost is high. These disadvantages limit the sale of curled yarnfabrics.

The present invention has for an object to prol vide an improved processfor curling yarns which will produce a superior product and which can beoperated expeditiously and economically.

Another object is to provide a process which will produce a uniformcurl.

Another object is to provide a process which Another object is toprovide a process whereby 55 shrinkage of the yarn during treatment iseliminated.-

Another object is to provide a process whereby the yarn will be slightlystretched during treatcurling which will cause the iinal product to beof the best quality.

\A further object is to provide a process in which the steepingoperation can be accomplished in a shorter time.4

A still further 4object is to provide for improved apparatus for use incurling yarn.

'I'he invention provides a process wherein a bundle of yarns is curledand while held under tension is steeped and dried and thereafter thetension is removed and the yarns untwisted. In the process to be moreparticularly described for the purposes ofillustrating the principles ofthe invention a bundle of yarns is twisted and simultaneously woundabout an incompressible mandrel which conveniently may be in the form ofa. wire large enough to serve the purpose of a substantially rigidmandrel for winding the yarn and yet suilciently small and flexible tobe conveniently coiled about a spool for convenience in furtherhandling. In this form there is no tendency to tangle and great lengthscan therefore be effectively and conveniently handled. The yarn thustwisted and coiled isv steeped as in previous processes, with thisdifference th'at` during the steeping operation it is so held on thewire mandrel as to prevent substantial shrinkage and as it is thereafterdried it stretches somewhat so that its final length is about 5% greaterthan before its original treatment.

'I'he degree of stretch or elongation can be controlled to some extentby varying the tightness of the twist and the degree of tension withwhich the yarn is wound about the wire mandrel.

The'degree and character of the curl produced can be considerablymodii'ledoto suit requirements by ,varying the number of yarns ir. thebundle.- l

the degree oftwist and the diameter of the wire mandrel.

The optimum degree of twist and direction of twist can be determined byexperiment-Tests made demonstrate that for most yarns the direction o'f.twist should be such as to reduce the twist which is imparted to theyarn in the doubling operation, that is to say the twist for curlingshould tend to untwist the yarn.

Certain definitel advantages such as relative uniformity of characterand size oi' the curl ofthe several yarns in one'bundle are obtained bytwisting the bundle once for each turn or wrap around the wire.

Actual practice of the invention has demonveniently obtained when theyarn is wound on a Wire mandrel with such tension as can readily beapplied and the yarn steeped as herein described.

It is to be noted that the 5% gain in the length of the yarn whentreated in accordance with the process of the present invention is to becontrasted with the 5% loss in length of the yarn treated by the processof the prior art and produces an effective gain in length of weavableyarn of about The new process, furthermore, produces a superior yarn inthat when the yarn in maintained under tension as described the severalfibres of the yarn shrink evenly thus avoiding the condition previouslyobtaining in which some fibres of the yarn shrink excessively and in usetake more than their share of the tension and are readily broken.

Comparative abrasive wear tests of fabric woven from yarn curled by thenew process and similar fabric woven from yarn of the vsame count curledby the process of the vprior art has shown the former to have far betterwearing qualities. The yarn curled by the new process alsoshows aconsiderably superior covering of the pile due to the superior type ofcurl produced. In other words, the stretching of the yarn, thusproducing a curled yarn of slightly less weight per thousand yards, ismorev than compensated for by the superior character of the curlobtained.

It has been found that the curl can be set in a considerably shortertimeby the process herein described than when the yarn is curled by theprocess heretofore used. Furthermore, yarns which could not heretoforebe satisfactorily curled by the commercialprocess are given asatisfactory permanent curl by the improved process. Mohair yarn can becurled by steeping for about one-third or one-half the time previouslyfound necessary, for example' for 2 to 4 hours. The curl in celluloseacetate yarn can be set by steeping in boiling water for about fifteenminutes.

Ordinary wool yarn should be steeped about 2 to 4 hours.

Cotton and regenerated cellulose (as-viscos yarns arepreferably'impregnated or at leastA vto fix the curl. c

wrapped rmly on the wire core causes a squeezing pressure on the fibreand at the same time causes, in effect, a stretching of the bre whichtends to force out the iiuid in the minute cell pockets in the fibres ofthe yarn, thus collapsing them and causing the yarn quickly to assume apermanent curl or kink. The provision whereby the yarn is given thecorrect twist, that is to say the better direction and the best degreeof twist, before steeping also contributes materially to the eiliciencyof the steeping and reduces the time necessary. Whatever the reason forthe results obtained, careful testshave demonstrated that the time ofsteeping is greatly reduced, the deterioration oi' the yarn iscorrespondingly reduced and a curled yarn of better physical propertiesis obtained by the process of this invention. Comparative tests havelshown a thirty to forty per cent greater tensile and elongation strengthin yarn curled by thenew process as compared with the prior art processhereinabove described.

The entire lot of yarn as -wrapped on the wire can be introduced at onetime into the steeping tank and treated for the desired period of time,or the yarn on the wire may be fed slowly through a steeping tank thelength of wire in the tank and the speed of feed being such as toprovide the desired treatment. `As the wire leaves the steeping tank itmay be passed through a drying chamber and immediately unwound in asuitable machine, thus providing a continuous operation. It can even beunwound before drying to advantage in some variation of the process.

The method of twisting the yarn and wrapping it uniformly on the wiremandrel avoids tangling o! the yarn and resultant difilculties inuntwisting.

The invention further provides apparatus for effectivelytwisting thebundle of yarns, winding the twisted bundle on the wire mandrel fortreatment and after treatment unwinding and untwisting the same andrewinding the separated yarns on a suitable spool or spindle.

For the purposes of disclosure an apparatus embodying principles of theinvention and` adapted for use in practicing the process will bedescribed, for the purposes of which description reference should be hadto the accompanying drawing forming a part hereof and in which- Figure 1is a view partly in side elevation and partly in central longitudinalsection showing the illustrative apparatus,

\ Fig. 2 is a plan view of the same, and l Fig. 3 is an enlarged detailview showing the wire core with a bundle of yarn twisted and woundthereon.

`lThe drawing is largely diagrammatic and intended only to illustrateprinciples of the apparatus without an attempt to provide an optimummechanical construction.

'Y lustration comprises an unwinding cradle 5 for Itis believed that theprincipal reason thatr.

the set of the curl can be produced eectively by steeping for a shortertime is that the yarn is under tension in curled form and ineect thefibres are stretched during the shrinking. It is believed also that thetension caused by removing curled and treated yarn from the wire mandreland -a winding cradle 6 for applying a fresh charge oi.' yarn to thewire for treatment;

A shaft I driven by the motor 8 supplies power to the machine. Thecradle 5 is rotatably mounted in the pillow blocks 9 and Illvsecured tothe main casing 'Il and is positively driven from the shaft '|by a chaingearing I2. A'yoke l5 s rotatably or iloatinglymounted in the cradle 5in bearings which are co-axial with the bearsteeping as the yarn tendsto shrink while ings of the cradle. The cradle, therefore, may

mandrel 25 with a fresh charge ofcurled yarn is wound. Both cradlesrotate in the same direction and both yokes are weighted to preventrotation thereof with the cradles. The wire mandrel is led from thespool I1 through guides 26, 21, 23 and 29 to the spool 24 on which it iswound. The spool 24 is driven by the motor 30 through a suitablefriction belt gearing which will maintain suilicient tension on the wirebut which will yield to prevent excessive tension. As shown, a yieldablefriction clutch 3| is provided for the Purpose of permitting adjustmentof the tension.

the wire. Fig. 3, indicates the condition of the yarn a as twisted andwound on the wire 25. A reverse twist of the bundle is to say a twist ofthe bundle which will tend to untwist the yarn.

A traverse mechanism for controllingthe winding of the wirel with itsload oi.' yarn on the spool 24 is conventionally indicated at 58. 'I'histraverse comprises a star wheel 59 which is engaged by a pin 60projecting axially from-thespool 24. t

In the arrangement shown the cradle 6 is designed to give one twistl tothe bundle of yarnA as it winds the twisted yarn once around the wiremandrel. This arrangement has been found to provide a satisfactory curlfor the yarns with which experiments have been made. Obviously, however,any desired number of twists per wind may be obtained by a suitablegearing arrange-,

ment.

Various modifications of the apparatus shown I obviously may be madewithout departing from The wire mandrel 25 is fed in accurate timedrelation to the speed of rotation of the cradles by means of a capstandrum positively driven from the shaft 1 and about which the 'wire iswrapped once or several times to maintain the required traction.

The cradle 5 unwinds the yarn from the wire and simultaneously untwistsit.' As shown, the yarn passes from the point of unwinding totheeccentric guide 35 and through the -tube 31 to exitat a point co-axialwith the cradle and whence it passes through a traverse conventionallyillustrated at 38 which lcan have one guidingl eye for each yarn, andthence to the spool 40 on which the several yarns are wound as is commonpractice in winding warp beams. The spool 43 is carried on the shaft 4|which is driven from the shaft 1 through belt gearing whichWillvmaintain the desired tension on the yarn but will slip to preventexcessive tension. In the arrangement shown the tension of the belt 42on the pulleys 43 and 44 is such as to suitably drive the spool butpermit slip when necessary to avoid excessive tension.` 'I'he traverse38 isconventionally indicated as mounted on a pivot 45 about which it isgiven a rocking movement by a cam 46 on the shaft 1.

A fresh supply of yarn is twisted and wound upon the mandrel from whichthe curled and treated yarn has been removed.l For this purpose a chargeof yarn is drawn from the spool 50 from -which it is guided to thewinding cradle Suitable tension on the yarn is maintained by means of abrake 5| engaging a brake drum l to provide any desired twist.Obviously, it is a 52 secured to the shaft 53 on which the spool 50 ismounted. This form of support for the yarn to be curled is illustrativemerely as obviously g the several separate yarns canbe Supported in anysuitable manner, as b'y separate spools or spindles suitably arranged.

In order that the twisting of the yarn, if it be a bundle of yarns, maybe confined to a reasonably short length a dividing pin 54 is positionedat a suitable distance from the end of the winding cradle 6. 'Iheseveral yarns are separated by this pin into two groups and from thedividing pin they pass through a guide 55 and thence to the tubularelement 55 which serves as the yarn guide of the cradle 6.

The yarn leaves the tube 55 through an eccentric guide 51 from which itis wrapped about the spirit of the invention.

The direction of twist shown is such as to untwist the yarn and this hasbeen found preferable in curling most yarn, but obviously the directionof twist and the extent of twist may be varied to suit the particularyarn treated and the optimum conditions are readily ascertained byexperiment. When analyzing the conditions of twist not only the twist ofthe yarn as a whole .but the effect on the twist of the strands makingup the yarn should also be considered. In order to-obtain greater orless twist the yarn carrying spools can be mounted in rotatable cradlesdriven simple matter in view of the state of the art to devise gearingincluding for example planetary gearing for providing the necessaryrotations and drive for the spools.

.If it is found desirable to adjust the speed of the drive of the wireautomatically more accurately to accommodate the drive ofthe wire to thepitch of the previously wound yarn, a

. variable Speed drive may be substituted -for the capstan drive shownand the speed may be controlled in response to a feeler mechanism havinga yarn guide closely adjacent the point of unwinding. Y

The wire may be made of any suitable material resistant to the action ofmoisture or any treating solution which may be used in the processing ofthe yarn, such for example as stainless steel.

wire at the If the wire is to be heated by an electric current during'the treatment or drying' of the yarn, the composition of the wire may beselected'with this purpose in mind. The wire should be sufiicientiystiff to serve as a relatively rigid mandrel but as' flexible as isnecessary for winding on the spools used.

The forgoing particular description lis illustrative merely and is notintended as defining the limits of the invention.

I claim:

1. 'I'he method of curling yarn which comprises winding the yarn undertension on an incompressible mandrel, treating the yarn at hightemperature to set the curl and unwinding the yarn for use. f

2. The method o! curling yarn which comprises winding the yarn undertension on a flexible Wire. coiling the wire with the yarn thereon, andtreating the yarn on the w'ire at a high temperature to set the curl.

3. The method of curling yarn which comis indicated, that' prisescombining a number of yarns in a bundle, twisting and winding the bundlearound an incompressible, substantially rigid core to form a curl ineach yarn, the number of twists of the bundle being substantially equalto the number of turns about the core, and treating the yarn to set thecurl.

4. The method of curling yarn which comprises twisting a number of yarnstogether, winding the twisted yarns under tension on an incompressiblemandrel, treating vthe yarn to set the curl, unwinding the yarn from themandrel and simultaneously untwisting the yarns.

5. The method of curling yarn which comprises twisting a number of yarnstogether, winding the twisted yarns on an incompressible mandrel,

steeping the yarn to set the curl, and unwinding the yarn from themandrel and untwisting the same.

6. The method of curling yarn which comprises combining a number ofyarns into a bundle,

twisting the bundle, winding the twisted bundle oi yarn under tensionon'a wire, steeplng and drying the yarn while still wound on the wireand unwinding and untwisting the yarn.

7. The method of curling yarn which comprises combininga number of yarnsinto a bundle,

twisting the bundle of yarns and winding the same on an incompressiblemandrel, treating the yarn while twisted and wound on the mandrel -3further characterized by the direction of twist given to the yarn beingopposite to the original direction o f twist of the yarn.

10. The method of curling yarn which cornprises combining a number ofyarns into a bundle, twisting the bundle and winding the yarn on anincompressible mandrel under substantial ten-l sion, steeping, dryingand unwinding the yarn from said mandrel and untwisting and separatingthe yarns. l

l1. The method of curling yarn which comprises combinlng a number ofyarns into a bundle, twisting the bundle of yarns and winding the sameon an incompressible mandrel, saturating the yarn with a solution of aresinuous material capable of providing a set in the yarn, removing thesolvent and unwinding the yarn from the mandrel and untwisting the same.

ANDREW LANGSTAFF JOHNSTON. J n.

